From the moon to Mars, to other planets and comets, stargazers have long speculated that there's water in outer space--and wondered how the heck it got there. The obsession continues because the presence of liquid water is thought to be the most promising indicator for life. Though there's been plenty of news in the past 50 years that there might be water on the moon and Mars, it's never been confirmed--until now. The road toward water on other planets, however, has been littered with discovery and disappointment, as this timeline shows.

1877 /// Italian astronomer Giovanni Schiaparelli sketches a series of channels (originally mistranslated as "canals" from the Italian word canali) that he's observed on Mars's surface through a telescope, and goes on to name what he perceives as bodies of water on the planet.

1893 /// Grove Karl Gilbert, observing the moon, suggests that its craters are formed not by volcanic activity, but by impacts from celestial bodies, such as asteroids. This leads to a popular notion that asteroids bombarding the Earth 3.8 billion years ago brought water to the planet.

1894-1906 /// American astronomer Percival Lowell, intrigued by Schiaparelli's illustrations, spends years studying Mars and publishes several books, including Mars in 1895 and Mars and Its Canals in 1906. Lowell maintains that there are features on the planet's surface that are not natural, and his work advances theories that intelligent life forms inhabit Mars and have set up irrigation canals.

1907 /// British naturalist Alfred Russel Wallace publishes Is Mars Habitable?, one of the early publications about the planet to focus on disciplined scientific reasoning rather than observation. Wallace disputes Lowell's claims of canals filled with liquid water, estimating that low atmospheric pressure and a colder climate than usually thought made the presence of water--and intelligent life--unlikely.

1969 /// Apollo 11 lands on the moon, and its crew confirms with direct observation what many suspected: The lunar surface contains no visible liquid water. This does not disprove speculation, however, that the moon may have water underneath its surface, or that its craters once contained H20 brought by water-bearing comets and asteroids.

1999 /// The Hubble telescope passes close enough to Mars to snap four images encompassing the entire planet's surface. Mars is shown to have north and south poles of what look like ice, just as Earth does. Until it's studied with certainty, researchers can only cautiously accept the presence of frozen water on Mars.

2002 /// Astronomers in Hawaii observe a main-belt comet, 133P/Elst-Pizarro, leaving a long, dusty trail of what appears to be icy comets in its wake. This furthers the notion that comets contain reservoirs of water and that their impacts onto planets' surfaces make it possible for bodies of water to exist beyond Earth. The observations are reinforced in 2005 with the study of the comet-like features of Asteroid 118401 which follows along the same orbital belt as 133P/Elst-Pizarro and leaves the same curious trail. Asteroid 118401 helped solidify the theory that asteroids may contain smaller amounts of ice than comets, and could also deliver water to planets on impact.

2004 /// The Mars Express Orbiter sent to the planet by the European Space Agency finds evidence of a permafrost of water ice at Mars's south pole when it maps the region using infrared technology. The ice is believed to be mixed with dark soil, which is why it wasn't detected before. This is some of the strongest evidence we have that there is ice on Mars, though the Mars Express Mission's lander, the Beagle, loses contact with the orbiter when it lands so it is never able to confirm the results with "hands on" robotic instruments.

May 25, 2008 /// The Phoenix robotic lander reaches Mars, and soon after it's observed that there is a shiny deposit within its area of operation, which is excitedly speculated to be ice.

June 20, 2008 /// The first confirmation that the deposit may in fact be ice, and is in reach of the Phoenix lander's arm, though it has yet to be analyzed.

July 18, 2008 /// The Phoenix lander's methods for collection of an ice sample meet with limited success, as it's found that much of the sample is prematurely heated by the robot's tools before being scooped up for analysis.

July 26, 2008 /// The Phoenix lander team uses what it's learned from scraping away at the ice sample known as "Snow White" and manages to procure enough icy soil for testing. While the sample is not perfect, the lander finally has enough to work with, and we will soon know what it has found.

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